Neutron2K's Computing Tutorials

Upgrading your Computers Random Access Memory (RAM)

Increasing the amount of Physical Memory your computer has is the most basic, and the most commonly performed upgrade in the world. Its purpose is to help increase the performance of the computer, although it is commonly misconceived as making the computer faster, but this is not the case.

Increasing the amount of RAM your computer has access to, does increase the running speed of some applications, (games more than anything), but it is not usually noticeable except for a difference in loading times, and this increase is based on how much additional memory you add to the computer.

What is Random Access Memory?

Random Access Memory (RAM) is a temporary memory that your computer uses to hold instructions that are waiting to be passed onto the Central Processing Unit (CPU) for execution. The more RAM you have in a computer, the more instructions you can queue up, thus improving your computers performance. There are many types of RAM available, and this opens up a whole new world of terminology. Types of computer memory are: EDO, D-RAM, SD-RAM, DDR, DDR2, RDD. RAM is only a temporary storage area and it is wiped every time you turn your computer off.

Different RAM Form Factors (Physical Attributes)

There are a number of ways that RAM can be categorized, such as Physical Form, Speeds, and Memory Type. The easiest way to start is to categorize by Physical Form. The Form Factor of memory is used to describe the memory modules physical attributes, such as size and pin count. Most computer motherboards will only support one type of Memory Form Factor.

The next few paragraphs detail the various Forms computer RAM is available in.

Single Inline Memory Modules (SIMM's)

SIMM's are an older type of memory and are starting to phase out. SIMM stands for Single Inline Memory Module and are available in two version, 30 pin and 72 pin. All SIMM's need to be installed in matching pairs. I.E. to Add 32MB of RAM to a computer that uses SIMM's, you would need to install 2x16MB SIMM's.

SIMM's are basically a modular printed circuit board (PCB), on which the memory chips are soldered. SIMM's are inserted into a socket much like the other RAM Form Factors that will be discussed here.

The two different pin sets (30 and 72) dictate the speed of the memory in the case of SIMM's. The 30 pin modules are older format and send data at a rate of 8 bits at a time. The later 72 pin versions that were introduced when processors started getting faster are used to transmit 32 Bit chunks at a time.

The way in which the two different types of SIMM can be identified is straight forward. 72 pin SIMM's are about 3/4 of an inch longer than the 30 pin version and they also have a notch in the Printed Circuit Board (PCB), in the lower middle. 30 pin SIMMs are about 3 1/2 inch's long in size, making 72 pin SIMM's about 4-1/4" long in total.

Dual Inline Memory Modules (DIMM's)

Very similar to SIMM's in physical appearance, DIMM's are also Memory Chips soldered onto a Printed Circuit Board (PCB). They are also slotted into a socket on the motherboard, but unlike SIMM's, they do not need to be installed in pairs.

The other differences of DIMM's is that they are longer and have 168 Pins. They are also a lot faster than SIMM's, transferring data at up to 64 bits in one go, (on systems that support the new 64 bit bus).

Another physical difference is that most SIMM's install into the motherboard sockets at a slight angle, where as DIMM's slide straight in vertically. DIMM's also have a different number of notches.

Other Various RAM Memory Form Factors

There are other types of memory available for laptops and such that are not covered in this document. These are:

SO-DIMM

MicroDIMM

RIMM

SO-RIMM

Different RAM Technology

The next part of Computer RAM we need to look at is the different types of technology that RAM uses. Just because a RAM Memory Module conforms to a Form Factor as detailed above, does not mean that uses the same technology as another memory module of the same Form Factor.

For example, if you picked up two DIMM memory modules from a mixed box, there's no guarantee they would be compatible in the same system. Whilst one of the DIMM's might be say, a DDR233 module, the other could be an older PC-100 SDRAM module. This part of the tutorial details some of the different kinds of RAM available, technology wise.

Some various types of RAM technology that you might of heard of are:

SRAM
DRAM
SDRAM
PC 100/133 SDRAM
DDR SDRAM
DDR2 SDRAM

The differences between these types of RAM will not be covered in this document. The main difference is the speed at which they run at. DDR2 is the latest kind of memory at the time of writing this and it offers extremely fast transfer speeds.

What RAM for your System?

Now we have a brief understanding of the various Physical Form Factors and types of Memory that are available on the market, how do you know what kind of RAM you need for your computer?

For most practical reasons, it's usually a given these days that for a desktop PC you will need a Dual Inline Memory Module for your computer, but which type can often prove problematic finding out if you don't know much about your computer, or indeed computers in general. As mentioned above, just because your motherboard has DIMM sockets, does not mean you can throw any old DIMM in there and expect it to work.

Most of the memory technologies available such as SDRAM and DDR come in a variety of speeds and these can be mixed. I.e. DDR2700 can be installed in the same motherboard as a DDR3200 module. However, only the speed of the slower memory will be used for all of the memory modules installed, regardless of how much faster they can perform. Also, there is a maximum speed of memory that your motherboard will support so if you installed a DDR3200 module into a motherboard that can only handle DDR2700, then the DDR3200 module will only run as if it was a DDR2700 module.

Now that we have that out of the way, there are three things you can do to determine what type of Memory Modules you need for your computer.

The first and most logical thing to do would be to look up the make and model of your motherboard on the internet and find out what memory types it supports. That way you do not need to open your system more than once, and you don't have to do the ground work to determine what speed memory you need to buy.

Unfortunately this isn't always an option so the first step to finding out the type of memory you have in your system would be to check your computers Power On Self Test (POST) screen. The Post screen is usually displayed after you first turn on your computer and it has counted the memory etc. If you have a computer that has a logo screen instead, this can usually be closed by pressing certain key on the keyboard such as tab or f2. If you cannot find the key, look to disable it in the systems BIOS.

When you see the information about your computers hardware popup, hit the pause key on your keyboard before it disappears. It will go quick so be ready. You should be able to determine the type of memory from the information provided by this screen, such as how much memory you currently have and how fast it is. Make a note of this information. Usually this will be enough to ask for guidance at your computer store.

To find out the Form Factor of memory you need, you will need to open your computer and examine the Memory Slots on the motherboard.

Once you have the required information, you can go and purchase your new memory!

Installing your New Memory

Once you have purchased your new memory, you can start the process of installing it. You should make sure that you are in a static free environment before starting and make sure you have everything to hand. Check my tutorial on Computer Hardware Tools to see what you may need during the operation, and ensure you are discharged of any static electricity before handling the memory. If you have an anti static wrist strap,you should use this by attaching the crocodile clip to a metal part of the computers chassis. If you do not have access to one of these tools, then you should ensure that you leave the computer power cord in, although switch off at the wall and the power supply unit, and then discharge yourself by touching the metal case of the computer for about 30 seconds.

You can then install our memory.

Checking your New Memory

Once you have installed your new memory, you can check to see if it is installed correctly in a number of ways. The first is to check the values on the Power On Self Test (Post) report screen, or when you are in windows, bring up the device manager by pressing CTRL+BREAK on the computers keyboard. The amount of Physical RAM should be displayed on the first page.